The present invention relates to compositions useful as biocides for the control of harmful microorganisms. More particularly the invention relates to phosphorus-based compositions possessing outstanding biocidical properties for a wide spectrum of applications.
As known, a phenomenon which occurs in industrial process systems and products as well as in natural materials and their processing is the development of contamination by microorganisms if means are not taken to inhibit their growth. Wood pulp, wood chips, starch and proteinaceous substances, animal hides, vegetable tanning liquors and leather and damaged or degraded by bacteria and other microorganisms or by enzymes produced by their growth.
Plants, in growth and in storage, as well as plant products are subject to microbiological contamination. Wet pulp containing about 25% moisture content is subject to attack by stain, mold, and decay fungi. If not controlled, the result is a loss of useful fiber in badly decayed pulp, difficulty in dispersing partially decayed pulp, a darkening in colour and the development of undesirable odors caused by the growth of the microorganisms. Different species of molds are encountered at various stages in the manufacture of leather. As an example, soaking provides an environment highly conducive to the growth of microorganisms, and even strongly pickled solutions are subject to attack by some microorganisms. Molds in particular may be troublesome and cause discoloration of the pickled stock, especially if it is held for a period of time. During the chrome tanning process, the chrome tanned stock held "in the blue" readily molds and is discoloured. Mold growth may also develop on heavy vegetable tanned leather during the drying period and produces spots and stains on either the flesh or grains sides. Other fields where the problem exists are petroleum drilling operations, metal working fluids and in the paint industry. Paint latexes can be destroyed and paint films deteriorate as a result of the attack of harmful microorganisms. Cooling towers can be adversely affected by biocontamination.
Another objectionable occurance in industrial process systems involving water is slime formation. Slime consists of matted deposits of microorganisms, fibers, and debris, and it may have a disagreable odor. The microorganisms involved in its formation are primarily various species of spore-forming and non-spore forming bacteria, particularly capsulated forms of bacteria which secrete gelatinous substances that envelop or encase the cells. Slime microorganisms also include filamentous bacteria, filamentous fungi of the mold type, yeast and yeast-like organisms.
Besides being objectionable from the standpoint of general cleanliness and sanitation in breweries, wineries, dairies, paper mills or other industrial plants or establishments, slime may interfere and produce plugging of screens in pulp and paper systems, thus reducing their efficiency. When large amounts of slime become incorporated in the paper sheet, its strength is reduced, and it may consequently break and require rethreading of the machine. In the paper itself, slime may be responsible for unsightly spots, holes and odors and may produce general discoloration throughout the sheet.
A large number of prior patents claim various compounds as biocides for the control of harmful organisms. Thus according to U.K. Patent Application No. 2,077,713, a mixture of iodoacetamides with amines or quaternary ammonium compounds is claimed for the control of microorganisms in swimming pools, ponds, cooling water, systems involving cellulosic compositions and starch pastes. U.S. Pat. No. 4,285,765 claims a synergistic microbiocidal composition comprising 2-(thiocyanomethylthio)-benzothiazole and 2,2-dibromo-3-nitrilopionamide. Preparations containing phosphorus and halogen-containing condensation products useful as insecticides are claimed in the U.S. Pat. No. 2,995,486. However, reagents which are effective as insecticides are often not effective against the broad spectrum of microorganisms encountered in the various industrial applications.